Double-throw switch mechanism



Sept. 18,1945. 1.. PIERCE DOUBLE-THROW SWITCH MECHANISM Filed Jan. 14, 1944 Q Sheets-Sheet 1 INVENTOR Lawrence f z'erce.

WITNESSES:

A'ITORNEY Sept. 18; 1945. i L. PIERCE 2,335,025

DOUBLE-THROW SWITCH MECHANISM Filed Jan. 14, 1944 2 Sheets-Sheet 2 WITNESSES: INVENTOR a I I ,9, Lawrence Herce.

' ATTORNEY Patented Sept. 18, 1945 DOUBLE-THROW SWITCH MECHANISM Lawrence Pierce, Edgewood, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 14, 1944, Serial No. 518,213

(01. {Yet-97) 11 Claims.

My'invention relates to mechanism for electric switches, and has for its general object to provide a mechanism for double-throw operation whose driven member performs a snap action when moving from anyone to another of its three operating positions.

More specifically, the invention aims at devising a double-throw mechanism operating with snap action when moving in either direction into or out of its center position, which is distinguished by a construction of simple design, easy to manufacture and assemble and of minimum space requirements.

It is also an object, related to the foregoing, to design the entire double-throw guide action mechanism so that it may be placed within, or integrated with, an operating handle suitable for use in connection with different types of contact devices.

It is further among the object of my invention to provide a double-throw switch mechanism in which a single spring is used for actuatwith a stationary pin. While this known mechanism is unsuitable for double-throw operation, the invention provides improvements that convert it into a double-throw switching device in accordance with the above-mentioned objects. This is achieved by providing the floating cam mechanism with stationary stop means which engage the cam portion of the floating member in two angularly spaced places so as to form three kinematic rest positions. According to a more specific feature of the invention, a rotatable driven member of the switch mechanism has two dog pins or the like coupling means for engaging the cam portion of the floating member, while a stationary part of the mechanism carries two stationary stop pins or the like abutments for providing the three just mentioned rest positions, these stationary abutments being spaced farther away from the shaft of the driven member than the dog pins 50 that the latter are provided with tw inner shoulders for engaging the dog pins of the driven switch member, and has two outer shoulders adjacent to the inner shoulders for abutting against the stationary stops, respectively, in order to limit the angular travel of the floating member.

The above-mentioned and other objects and features of my invention will be understood from the following description of the two embodiments illustrated in Figs. 1 through 9 and 10, respectively, of the drawings:

Figure 1 represents a switch mechanism according to theinvention by a sectional view extending in the radial plane denoted in Fig, 6 by the dash-and-dot line marked I-I, this figure showing the switch in its neutral or mid position;

Fig. 2 shows the same switch, also in section, with the switch handle moved towards the righthand position and the mechanism ready to be the mid position shown in Fig. 1;

Fig. 7 is a face view of the floating cam member of the mechanism according to Figs. 1 through 6;

Figs. 8 and 9 are axial and radial views respectively of the rotatable driven member of the mechanism; and

Fig. 10 is a section through a different modiflcation of my invention showing the mechanism in mid positioncomparable to that illustrated in Fig. 1.

Referring to Figs. 1 through 9, numeral [0 denotes as a whole the driving member of the switch. Numeral 20 represents as a whole the rotary driven member to be actuated by the driving member Ill with snap action between a mid position and two outer positions. Numeral 30 represents the floating cam member which is interposed between the driving member ID and the driven member in order to produce the just-mentioned snap motion. The numeral 4| (Fig. 6) refers to the stationary casing or frame structure of the switch which has parts for cooperation with the floating cam member and forms together with the cam member the three kinematic rest positions herebefore mentioned.

The driving member It forms a casing which encloses and protects the other individual elements of the mechanism. The driving member H3 has a substantially cylindrical portion H integral with a handle portion I2. A lug I3 is provided at the extreme end of the handle I2 and serves as an abutment for a coiled extension spring is which connects the driving member with the floating member 39. The portion H of the driving member has two projections l4 and I5 arranged at opposite sides of its inner periphery for cooperation with the floating member. A hub it forms an integral part with the other portions of the driving member ii] and has two lugs I? and 48 serving to establish a temporary positive engagement between the driving member and driven member.

The driven member 28 of the mechanism includes a shaft 2! whose extension 22 forms a crank for actuating a contact device housed in, or mounted on, the stationary structure 40 (Fig. 6). A crank plate 23 is firmly mounted on shaft 2! and carries two dog pins 24 and 25 which are angularly spaced from each other at equal distances from the shaft 2!. The crank plate 23 forms two shoulders 25 and 27 adjacent to the pins 2-4 and 25, respectively. When the driven member 2i! is assembled with the driving member lilas shown in Figs. 1 and 6, the shaft 21 of the driven member forms a pivot about which the driving member is rotatable. During such rotation, the dog pins 2t and 25 will establish a temporary looking or driving engagement with the floating cam member.

The floating cam member 39, as isbest apparent from Fig. 7, has an opening 31 which in the assembled condition surrounds the shaft 2! with sumc-ient play to permit the floating member to rotate about the shaft 21 as well as to perform a radial motion relative to the shaft. The lower portion of the opening 3] has a smaller width than the upper portion.

A larger opening of substantially arcuate shape is provided in the floating member 130 and extends symmetrical to opening 3|. The edge of opening 32 forms a notch at 3,3 in order to provide a suitable rest or abutment for the end of the spring is. The center portion of the arcuate opening 32 is bordered by a cam portion 34 whose lateral slopes terminate in two inner shoulders and 3%; which are bordered by outer shoulders 37 and 38, respectively. The outer peripheral dg of member 3!} forms two shoulders 39 and 40 for cooperation with the lugs l4 and 15 of the driving member ID.

The stationary casing or structure 4! has a bearing in which the shaft ill of the driven member 20 is journaled. Two stop pins 4'2 and 43 are firmly secured to the stationary structure and hence maintain a fixed position during the operation of the mechanism.

When the mechanism is assembled and placed in its mid position as represented by 'Figs. 1 and 6, the spring is pulls the floating member 30 towards the lug -3 so that the cam portion 34 of the floating member abuts against the stationary stop pins Q2 and 43 and thereby secures a rest position for the individual elements of the mechanism. In this position, the shoulders 35 and 36 of the floating member 30 engage the respective dog pins 24 and 25 of the driven member. thus determining a rest for the driven member. The shoulders 39 and 4B of the floating member 36 engage or lie close to the lugs l4 and $5 of the driving member [0. The lateral slopes of the cam portion 34 are preferably so shaped that their portions adjacent to the peak of the cam are substantially circular and have their center in the axes of dog pins 24 and 25, respectively.

Starting from this mid position of the mechanism (Fig. l) the operation of the switch is as follows. When the handle portion [2 of the driving member is turned clockwise, the spring is has the tendency to entrain the floating member in the same direction. However, since the cam portion 34 of the floating member is wedged between the stationary stops .42 and t3, the member is at first not free to follow this tendency. It merely performs an angular motion about the dog pin '24, During this initial motion of the floating member, no force is exerted on the dog pin 24, and since further this pin rests against the cam portion 34 which at the point of engagement extends substantially transverse to the path of rotation of pin 2 no rotation is imparted by the floating member 33 to the driven member 20.

As the rotation of the driving member ID proceeds, the force of spring H] acting on member 30 will cause the floating member to move .radially with respect to the shaft 2| until the peak of cam portion 3t passes underneath the stop pin 43. This intermediate stage of motion is represented in Fig. '2. In this position, the mechanism is ready to trip, that is, to release the driven member forrotary motion towards the right-hand position. The lug .l] of the hub portion i6 is so located that it engages or is about to engage the dog pin 24 in the just-mentioned tripping moment. Upon passing through this stage, the mechanism will permit the floating member 39 to, follow the angular motion of the driving member about shaft 2! and to entrain the driven member 29 due to the engagement of stop 34 with dog pin 24. If for any reason the driven member should be retarded, for instance, by friction or sticking in the contact device to be actuated, the positive engagement between lug H and dog pin 24 will overcome such initial friction and hence secure the desired snap action.

The maximum :deflect'ion reached 'by the driven member 20 is shown in Fig. 3. According to this figure, the cam portion '34 of the floating member '30 has passed beyond the'stop 43 and has permitted the spring 19 to move the member 30 radially towards the stop '13. The cam portion '34 has been forced to enter between pins 43 and 25 and, as a result, has rotated the driven mem- -ber23 and the shaft 2| with its crank 22 in the clockwise direction, thus placing the associated contact device of structure 40 into a corresponding contact position, When the floating member 30 reaches its end position, the stationary stop 32 is engaged by the outer shoulder '36 of the floating member and thus prevents further rotation of this member.

When turning the driving member J0 out .of its mid position, the outermost end position reached by the handle portion 12 is slightly in excess of the angular motion to be effected by the driven member in order to ascertain a safe snap action. This outermost position of the handle I2 is shown in Fig, 3. In this position, the shoulder 39 of the floating member may engage the lug l of the driving member. When new the handle I2 is released, the tension of the spring l9 will cause the driving'member I!) to effect a slight angular return movement towards the mid position. In its final position of rest, the spring l9 lies again symmetrically with respect to the driving member.

Starting now from the right-hand end position just described, let us assume that the driving member If! is turned back towards mid position. During the first portion of the handle motion, a rotation of the driven member 2 3 is prevented due to the fact that the dog pin 25 is engaged by the floating cam member while the latter is prevented from following the rotary motion of the driving member by the stationary stop 43. The frictional engagement of the contacts actuated by the driven member contributes also to retaining this member in its position of rest during this initial portion of the return motion of the driving member. The floating member 30, however, is forced to move so that cam 34 slides along pin 43 while the opposite inner edge of member 30 slides along pin 42. During the progress of this return motion, the mechanism will pass through the tripping position shown in Fig. 4. In this position, the radial motion of the cam member 34 towards the shaft 2| is at its maximum, and the peak of cam portion 34 is just underneath the stop pin 43. Upon passing through this phase of operation, the floating member 39 is free to rotate under snap action in the counter-clockwise direction until the cam portion 34 is again wedged between the stop pins 42 and 43. The mechanism then assumes the position of its individual elements shown in Fig. 1.

When turning the handle 52 of the driving member ID from the mid position of Fig. 1 towards the left-hand position, i. e., in counter- I clockwise direction, the floating member 30 is at first stopped by pin 42 and limited to a substantially rotational motion about the dog pin 24, simultaneously performing a substantially radial motion towards the shaft 2| until the peak of the cam 34 moves underneath the stop pin 42. tripping point, the floating member 39 rotates counterclockwise under snap action and entrains the driven member in a manner similar to the operation described in the foregoing. The final position reached by the mechanism is represented in Fig, 5. In this position, the further rotational motion of the floating member "3E! about the shaft 2! is stopped by the engagement of shoulder 38 with the stationary stop pin 43.

When turning the handle I2 from the lastmentioned left-hand position back to the midpoint position, the snap-action operation is similar to the one described previously in conjunction with Fig. 4 except that now the stop pin 42 serves to retain the floating member 30 until the mechanism passes through the tripping stage.

It will be apparent from the foregoing that the two stationary stops 4-2 and 43 are sufficiently spaced from the shaft 2| to offer a free passage to the dog pins 24 and 25, as well as the other parts of the driven member 20. For a proper operation the shoulders formed at the opposite ends of the arcuate opening 32 in the floating member 30 must be so formed that while they engage the dog pins 24 or 25, these shoulders Upon passage through this clearance or i do not interfere with the angular travel of the dog pins and the floatingmember relative to the stationary stops 42 and 43, with the exception of the right-hand and left-hand end positions in which the floating member 30 may directly engage the stationary stops 42 and 43 by the respective shoulders 31 and 38.

In order to permit a better understanding of the essential features of my invention as distinguished from those of mainly auxiliary nature, reference is had to the modification shown in Fig. 10. This modification is different in a number of individual features, but involves also the essential characteristics of my invention.

The driving member i9, according to Fig. 10,

has a substantially cylindrical housing portion II which forms two rods l4 and I5 for cooperation with a stationary stop pin 5%. This stop pin is firmly mounted on the stationary switch structure in addition to the stop pins 52 and 53 previously mentioned. When in operation," the angular motion of the driving member l0 about the shaft 2! is limited by the engagement of pin 54 with either the lug [4 or l5. 7

The driven member has a substantially triangular crank plate 23' providedwith two lugs 24' and 25', but having no shoulder portions comparable with shoulders 26 and 2"! in Fig. 8 for cooperation with the stop pins 52 and 53. These shoulders are unnecessary in the present embodiment because the motion of the driving member and the angular end position of the other elements of the mechanism are sufiiciently determined by the additional stationary stop 54 in coaction with the lugs I 4 and I5.

The floating member 30 has shoulders 35 and 36 for engaging the dog pins 24 and 25', and forms also a cam portion 34 for cooperation with the stop pins 52 and 53.

The hub portion 15' of the driving member ID differs from the one shown in the preceding embodiment by not containing lugs I l and [8, although such lugs could also'be provided if desired for greater reliability of operation. Similarly, the floating member 30, according to Fig. 10, is sim-: plifled and has no outer shoulders comparable with shoulders 38 and 39 of the floating member 30 previously described. It will be understood, however, that such auxiliary means may also be provided in the present modification.

When the driving member Ill is rotated from the illustrated mid position towards the left-hand or right-hand position, the spring l9 tends to entrain the floating member 39 in the same direction so that the latter causes the driven mem ber 20 to follow in the same direction of rotation. However, the motion of the floating member 30' is at first controlled by the cam engagement between the cam portion 34' and one of the stop pins 52 or 53, so that the member 30 is limited toa radial motion towards the shaft 2! until the tripping point is reached. Then the floating member 30' is released for snap action and the driven member is entrained in a manner similar to the operation described in conjunction with the embodiment of Figs. 1 through 9,

In view of the above elucidated possibility of providing the modified mechanisms without departin from the objects and essential features of my invention, I wish this specification to be understood as illustrative and not in a limiting sense.

I claim as my invention:

1. A double-throw switch mechanism comprising combination a rotatable driven member, a

coaxially rotatable driving member, a floating cam member for entraining said driven member, stationary stop means engaging said cam member so as to form three angularly spaced rest positions and two intermediate tripping positions, and a spring disposed between said driving member and said floating member for biasing it towards engagement with said driven member and said stop means.

2. A double-throw switch mechanism comprising in combination a rotatable driven member, a coaxially rotatable driving member, a floating member having two spaced shoulder portions for entraining said driven member for imparting thereto rotation in either direction and having a pointed cam portion intermediate said shoulder portions, two stationary stops angularly spaced from each other relative to the axis of rotation of said driven member for engaging said cam so as to form three angularly spaced rest positions and intermediate trippin positions for said floating member, and a spring disposed between said driving member and said floating member for biasing said floating member towards engagement with said driven member and said stops.

3. A double-throw switch mechanism comprising in combination a stationary structure, a shaft revolvable relative to said structure, a driven member mounted on said shaft and having two angularly spaced stop means, a driving member rotatable about said shaft, a floating member surrounding said shaft and being crotatable and radially displaceable relative thereto, said floating member having two angularly spaced shoulders for abutting against said stop means and a pointed cam between said shoulders, two angularly spaced stops mounted on said structure for engaging said cam so as to provide three angularly spaced rest positions and intermediate tripping positions for said floating member, and .a spring disposed between said driving member and said floating member for biasing it towards engagement with said driven member and said latter stop means.

4. A double-throw switch mechanism comprising in combination a rotatable driven member having two angularly spaced dog pins at equal distances from the axis of rotation, two stationary stops spaced angularly from each other and arranged at equal distances from said axis and farther away than said dog pins to permit the latter a free passage during rotation of said driven member, a floating member having tWo spaced shoulders for engaging said do pins respectively and forming a pointed cam between said shoulders for engaging said stops so as to have three angularly spaced rest positions and intermediate tripping positions, and a spring disposed between said driving member and said floating member for biasing it towards engagement with said dog pins and stops.

5. A double-throw switch mechanism comprising in combination a rotatable driven member having two angularly spaced dog pins at equal distances from the-axis of rotat-ion,tw o stationary stops spaced "angularly from each other and arranged at equal distances from said axis and farther away than said dog pins to permit the latter a free passage during rotation of said driven member, a floating member having two spaced inner shoulders for engaging said dog pins respectively, two outer shoulders adjacent to said respective inner shoulders for abutting against said stops respectively in order to limit the travel or said floating member, and a pointed cam formed between said inner shoulders for slidably engaging said stops so as to provide three angularly spaced rest positions and intermediate tripping positions for said floating member, and

.a spring disposed between said driving member and said floating member for biasing said floating member towards engagement with said dog pins and stops.

6. A double-throw switch mechanism comprising in combination a rotatable driven member having a shaft and two symmetrically arranged projections spaced equally from said shaft, two stationary stops angularly spaced from each other at equal radial distances from said shaft larger than those of said projections to permit the latter a free passage during rotation of said driven member, a floating member of flat and symmetrical shape having an opening elongated in the direction of the symmetry axis and surrounding said shaft so as to permit said floating member rotational and radial motion relative to said shaft and having also a generally arcuate edge forming a pointed cam with a cam point on said symmetry axis for engagement by said stops so as to provide for said floating member three angularly spaced rest positions with intermediate tripping positions, said edge forming two symmetrically arranged shoulders adjacent to said cam for engaging said projections respectively, and a spring disposed between said driving member and said floating member for biasing it towards engagement with said projections and stops.

'7. A double-throw switch mechanism comprising in combination a rotatable driven member,

a coaxially rotatable driving member, a floating member havinga centrally located cam and forming two abutments at both sides of said cam respectively for engaging said driven member, stationary stop means arranged in a fixed position relative to the axis of rotation of said driving and driven members for engagement by said cam so as to form three an-gularly spaced rest positions and intermediate tripping positions for said float ing member, said floating member having also shoulders for abutting in its two end positions against said stop means, and a spring disposed between said driving member and said floating member for biasing it towards engagement with said driven member and said stop means.

A double-throw switch mechanism comprising in combination a rotatable driven member having a shaft mid two symmetrically arranged projections spaced equall from said shaft, two stationary-stops angularly spaced from each other at equal radial distances from said shaft larger than'those of said projections to permit the latter a free passage during rotation of said driven member, a floating member of flat and symmetrical shape having an opening elongated in the direction of the symmetry axis and surrounding said shaft so as to permit said floating menrber --rota-ti.-onal and radial motion relative to said shaft andnaving also a generally arcuate edge forming a pointed cam with a cam point on said symmetry axis for engagement with said stops so as to provide for said floating member three angularly spaced rest positions with intermediate tripping positions, said edge forming two symmetrically arranged inner shoulders adjacent to said cam for engaging said projections respectively and two symmetrical outer shoulders for abutting in the two end positions against said stops when the latter are out of engagement with said cam, and

a spring disposed between said driving member and said floating member for biasing it towards engagement with said projections and stops.

9. A double-throw switch mechanism comprising in combination a rotatable driven member, a coaxially rotatable driving member, a floating member having two spaced shoulder portions for entraining said driven member for imparting thereto rotation in either direction and having a pointed cam portion intermediate said shoulder portions, two stationary stops angularly spaced from each other relative to the axis of rotation of said driven member for engaging said cam so as to form three angularly spaced rest positions and intermediate tripping positions for said floating member, said driven member and said floating member each forming two angularly spaced abutments for engaging a different one of said stops in either end position of rotation of said driven member and floating member, respectively.

10. A double-throw switch mechanism comprising in combination a shaft, a crank member rotatable about the axis of said shaft and having two projections spaced equally from said shaft and two abutments adjacent to said projections respectively and spaced from said shaft a larger distance than said projections, two angularly spaced stationary stops arranged in a fixed relation to said shaft axis for engagement by said a'butments respectively when said crank member is in either end position of its rotation, a floating member having an opening elongated in the direction of the symmetry axis and surrounding said shaft so as to permit said floating member rotational and radial motion relative to said shaft and having also a generally arcuate edge forming a pointed cam for engagement by said stops so as to provide for said floating member three angularly spaced rest positions with intermediate tripping positions, said edge forming two spaced shoulders for engaging said projections respectively and having two abutments for engaging said stops respectively in either end position of rotation of said floating member.

A double-throw switch mechanism comprising in combination a driving member and a driven member both movable between two end positions and an intermediate position, stationary stop means disposed in a fixed relation to the path of motion of said member so as to form abutments for limiting the motion of said driven member in said two end positions respectively, a cam member engaging said driven member and movable relative to said stop means and said driving and driven members along said path and towards and away from said stop means, said cam member being arranged for engaging said stop means so as to provide a rest in said intermediate position and tripping points between said three positions, and a spring disposed between said driving membe: and said cam member for elastically entraining the latter while biasing it towards engagement with said stop means and driven member in order to produce snap action for each change of position of said driven member.

LAWRENCE PIERCE. 

